Why did Apple heavily increase it’s Debt to Equity Ratio since 2016, eventhough it’s one of the most solvent Companies in the World?

I am relatively new to Finance and I have been asking this question for a while now. My assumptions are, that they were able to loan money at a very low interest rate due to their AAA creditworthiness and used it to finance projects + to reduce it's tax since interest expenses are not getting taxed. Are my assumptions right and are there points that I am missing?